Before typewriters and computers, individuals typically wrote using handheld writing implements, such as pens or pencils. In addition, even given the benefits of a keyboard and computer mouse, there are situations in which a user of an electronic device, such as, a personal computer, could benefit from using a pen-shaped writing implement to create information. In one example, a computer graphic artist may desire to draw something directly on the display screen of a computer. Certainly, the artist may rely on the mouse as an input device to the computer, however, while the mouse may provide the customized input, the mouse may not provide a sensitive and/or comfortable enough option for the artist who is accustomed to using a handheld pen to draw a picture.
One conventional product used to draw with a computer is the Wacom® pen tablet device. Specifically, the Wacom® Intuos® line of pen tablet devices provides a device that may accept pen movement by hand and relay that input to the computer display. These tablet products consist of a tablet and a pen-shaped stylus (i.e., pen shaped handheld device).
FIG. 1 illustrates an example of a conventional tablet device and a stylus 10 that may be handled by a user. Another example tablet may incorporate the use of a mouse (not shown). When the user moves the stylus pen on the tablet, the onscreen pointer moves in the same manner as a mouse. In effect, the mouse and mouse pad are replaced with the pen and the tablet.
The tablet, unlike the mouse pad, is not restricted to a horizontal plane since the stylus remains in the user's hand and is therefore still operable when the stylus is shifted outside of the tablet's plane. To the contrary, the mouse rests on the mouse pad and is subject to sliding off the pad. In addition to strictly 2-dimensional inputs from the user of a mouse (i.e., up/down and left/right), tablets are pressure sensitive so that the computer is provided with an additional input describing how hard the user is pressing the stylus into the tablet.
FIG. 2 illustrates a simplified drawing of the electronic components of a pen tablet device. Referring to FIG. 2, a stylus pen 20 and a tablet 30 are illustrated as having an amplifier component 41 and an A/C power source 42 as some basic components of the tablet's circuitry.
Due to the tablet's widespread success and acceptance, many popular software applications have been created with a user interface designed to accommodate a pen tablet as an input device. These software applications receive and process the same position inputs that would otherwise be generated from a computer mouse. For those signals associated with a pen tablet input, additional pressure sensors may also be used adding an additional input feature. For example, a graphics program such as Adobe Photoshop® could be used to create a thicker line onscreen when the user increases the downward pressure on the stylus. In addition, the tilt of the stylus may also be detected and used as an additional mode of input. The stylus can even be turned around so that the “eraser” end is used as yet another input type or input eraser.
While the pen tablet devices remain popular, they are not the only technology in existence that may be used to generate user handheld information. For instance, touch-screen devices are also types of hand initiated input devices. For example, Elo Touchdevices® are one brand of touch-screen monitors. Touch-screens generally are similar to pen tablets with a couple of differences. For example, with touch-screens, the stylus is always a passive device, and thus it could be a pen, a finger, or even the corner of a credit card that is used to touch the pad and generate an input. In addition, the tablet portion of touch-screen devices is built into the display itself. Therefore, a typical touch-screen device might be controlled by a user tapping and/or dragging a finger on the device's display, while a pen tablet device would combine a traditional display with a separate stylus and tablet.
FIG. 3 illustrates a touch-screen device in use. The monitor 31 provides a touch-screen that may be accessed by a user finger 50. The technology involved in detecting the position of a stylus (whether active or passive) on a screen (whether a tablet or a display) may be similar for both examples. For example, pen tablet devices in which the stylus is passive is similar to a touch-screen which is always passive. When referring to these example devices, the term “pen tablet device” will be used with the understanding that the touch-screen device may also be considered a particular type of a pen tablet device.
Generally, pen tablet devices include two components, which include the pen or stylus and the tablet. Some pen tablet devices utilize an “active” stylus, meaning that the stylus needs to be provided with a power supply in order to operate. Other types utilize a passive stylus whose position is detected by the active element in the tablet surface. These design factors influence the ultimate design of the devices since passive components can be made smaller and lighter, as well as wirelessly.
Although these above-noted technologies may be different, the technology employed for the detection process is not of great importance to the typical user. Rather, the manner in which the user interacts with the product is of greater importance to the user. In other words, most users don't have a preference whether a given device uses a touch-sensitive writing surface to detect position, or, if it instead uses passive or actively-generated magnetic fields to operate. The user is more concerned about features, such as, wired versus wireless operation, device weight, device precision and sensitivity, durability, and size.
Within the user's interaction, some features may be more important to the user. Obviously, a wireless tablet would have certain advantages over a wired tablet, however, perhaps a wireless stylus would be of less significance since the stylus is never far from the tablet.
With any pen tablet device, there is a concern that some amount of drift will occur. Generally, the accuracy of an electronic stylus data input device may only be as accurate as the amount of drift that occurs. One procedure to minimize the amount of drift that occurs is to perform a proper calibration procedure.
Certain tablet technologies rely on natural magnetic fields, which can be affected by various forms of interference, such as, metallic objects. If a pen tablet device is operating based on the predefined characteristic that the magnetic field environment is static, and the user is moving unexpectedly or a metallic object is brought near the surface of the tablet, then certain drift may be experienced compromising the user's writing experience (e.g., a truck drives towards the vicinity of the tablet device). Certainly, such a distraction will influence the magnetic field near the device and cause distortion.
These type of inertial devices measure their own movements using inertial sensors (e.g. gyroscopes and accelerometers) which provide readings as to how the devices have moved since they initially began receiving data measurements. These devices do not use a calibration procedure prior to allowing user input. As a result, small errors build up over time because the true position of the device and user's movements is not known.
For the magnetic case, the error could be from a shifting reference point due to the shifting magnetic field, while in the inertial case, the error may simply compound because the measurements are made with respect to the previously calculated position.
The user interaction is a factor to consider in the design of the pen tablet device. Nevertheless, there are numerous other features which may be exploited, such as, initial setup procedures, to expand the options, quality and overall performance available to the user.